The Nav system on my 06 Limited has been great, even on road trips to remote areas.....until now. Suddenly, I'm losing the GPS signal for several hours at a time in areas that I normally receive a signal. Because it occurs intermittently and not when I'm in my hometown, the dealer can't assess the problem. I've read the troubleshooting section of the manual, and that was no help. Has anyone else had a similar problem?? thanks